Diesel noob, starting problem.

[stuvy]

I just picked up an 89 Jetta Diesel. It started fine, drove for about 1hour on the highway, shut it off and it wouldn't start again.
There are air bubbles in the feed line from the filter. The car starts fine if you give it a decent push start.

I am thinking its an air leak in the feed line somewhere. But was also thinking it could not be turning over fast enough.

Could either/both of these be the culprits?

Is there anyway of getting the started to turn over faster?
Whats the best way of finding an air leak on the vacuum side?

Thanks in advance.

[Zulfiqar]

remove both lines and use some pressure setup to pressurize them, - that way the leak will show.

[stuvy]

The leak is somewhere before the filter, I can watch airbubbles come out of the filter and through the line (clear of course). There are lots of really really small ones.

It push starts great though.

[Zulfiqar]

have u tried changing the filter itself?

and the one culprit is the water separator under the car - it goes bad and admits air into the system too.